The film is based on the Red Ball Express convoys that took place after the D-Day landings in Normandy in June 1944.

One racially integrated platoon of this Red Ball Express encounters private enmities, German resistance, minefields, and increasingly perilous missions.

Major General Frank Ross, who was in charge of the actual Red Ball Express, acted as a technical adviser.

[3] Because of the high percentage of African-American drivers in the Red Ball Express operation, the Department of Defense insisted to Universal that the film be modified so that "the positive angle be emphasized" regarding race relations.

Director Budd Boetticher claimed: The army wouldn't let us tell the truth about the black troops because the government figured they were expendable.